Paper 2

State the most appropriate instrument for measuring the peak value of an oscillating voltage

Cathode Ray Oscilloscope

Define the torque of a couple

product of force and perpendicular distance between forces

State the type of emission that is not affected by electric and magnetic fields

Gamma

State the type of emission that has a range of energies, rather than discrete values

Beta

State Kirchoff’s second law

Sum of electromotive force = sum of potential differences around a closed loop

(To do with conservation of energy)

Explain what is meant by frequency for a wave on the surface of water

number of wavefronts passing a point per unit time

State what is meant by an alpha particle

A helium nucleus

State the conditions for the formation of stationary waves

• two waves of same speed travelling in opposite directions overlap

• waves are the same type and have same frequency and wavelength

State Newton’s first law of motion

A body continues at rest or constant velocity unless acted upon by a resultant force

State what is meant by the mass of a body

• the quantity that resists changes in motion

• OR the quantity of matter in a body

For a progressive wave, state what is meant by the wavelength

the distance between two adjacent wavefronts

Define displacement

Distance from a fixed point in a specified direction

Describe one cause of a random error and systematic error in measurements of a constant current taken using an analogue ammeter

Random:

• wrongly interpolating between scale divisions

• reading scale from different angles

Systematic:

• zero error

• wrongly calibrated scale

Describe the energy conversion that occurs when a particle is falling through the air at constant speed

GPE to thermal energy

State the principle of superposition

Two waves meet at a point/overlap.

Resultant displacement is vector sum of individual displacements.

Why does beta decay have a range of energies?

• three body decay

• energy from decay is shared randomly between an electron, daughter nucleus, and anti-neutrino

What are the SI base units

Mass (kg)

Length (m)

Time (s)

Current (A)

Temperature (K)

Describe the concept of weight

The effect of a gravitational field on a mass

Principle of conservation of momentum

• linear momentum always conserved with no external forces

State the effects in an elastic collision on the total kinetic energy and relative speed of approach vs separation

KE is conserved

relative speed of approach = relative speed of separation

How do you find relative speed of approach/separation?

u(1) - u(2) = v(2) - v(1)

What defines an inelastic collision

Momentum always conserved

Some change in KE may take place. (Could be lost to surroundings via deformation, heat)

What is a couple

a pair of forces that acts to produce rotation only

Define pressure

Force perpendicular to a surface per unit area

What is the origin of upthrust acting on an object in a fluid?

• it is due to a difference in hydrostatic pressure

• pressure increases with depth

• pressure acting upwards greater than pressure acting downwards on object

• so force is exerted upwards on object

What is the equation for upthrust force

(Archimedes principle - upthrust is equal to weight of fluid it displaces)

F = density x volume x g

What is the equation for hydrostatic pressure

change in pressure = density (of fluid) x g x depth in fluid

Define load

The tensile force that causes the extension

What is the compression

Original length - reduced length

What is Hooke’s law

The extension of an object is proportional to the applied load, given temperature stays constant and the limit of proportionality is not exceeded.

What is the limit of proportionality

The point up to which the force is directly proportional to extension

What is the spring constant of an object

The force per unit extension

What two numbers are conserved in nuclear processes

nucleon number

charge (lepton number)

What particles are released in Beta minus radiation

Electron, (electron) anti-neutrino, and daughter nucleus

What particles are released in beta plus radiation

positron, neutrino

Why are electron anti/neutrinos produced in beta decay

• to conserve lepton numbers, and energy-momentum

Electron anti-neutrino has a lepton number of -1

an electron neutrino has a lepton number of +1

What is the lepton number of an electron

+1

What are the six flavours of quarks

Up, down, strange, charm, top, bottom

What is the relationship between: hadrons, mesons, baryons, and leptons

Hadrons: particles that have quarks

Mesons: two quarks (1, 1 anti)

Baryons: three quarks

Leptons: do not feel the strong force

Define the electromotive force

energy transferred per unit charge in driving charge around a complete circuit

Transverse vs longitudinal waves

• transverse can be polarised

• transverse: direction of energy propagation perpendicular to direction of oscillations

Define wavelength

Minimum distance between particles which are vibrating in phase

or distance between adjacent wavefronts

What is a property of all waves

• can be reflected and refracted

• can produce interference patterns

What is the Doppler effect

the frequency change due to the relative motion between a wave source and an observer

Why do electromagnetic waves differ to other types of transverse waves

• don’t need a medium to travel through

If a wave slows down, what changes and what remains constant

• frequency remains constant

• wavelength decreases

What is the electromagnetic spectrum in order of longest wavelength to shortest

Radio

Micro

Infrared

Visible

Ultraviolet

X-rays

Gamma rays

Give approximate wavelength range for radio

10e4 - 10e-1

Give approximate wavelength range for microwaves

10e-1 to 10e-3

Give approximate wavelength range for infrared

10e-6 to 10e-2

Give approximate wavelength range for visible

7 × 10e-7 to 4 × 10e-7

Give approximate wavelength range for ultraviolet

10e-7 to 10e-9

Give approximate wavelength range for X-rays

10e-9 to 10e-12

Give approximate wavelength range for gamma rays

10e-10 to 10e-16

Define a polarised wave

A transverse wave in which vibrations occur in only one of the directions perpendicular to the propagation of energy

What is the condition for a wave to be plane polarised

• vibrations in just one plane

• in the direction the wave energy is travelling

What is Malus’ law

Where Inought is the plane polarised intensity (or I is the intensity that passes through the analyser).

The angle between polarisation direction and analyser axis.

What conditions must be the case to produce an observable interference pattern/

• same frequency

• constant phase difference

Described as coherent sources.

What is a stationary wave

two waves travelling with same speed in opposite direction along the same line overlap, hence interfere. Same frequency, same amplitude, same wavelength.

What is the fundamental frequency/first harmonic

lowest frequency at which stationary wave forms (1 antinode, 2 nodes).

How do you find the frequency of the second harmonic from the frequency of the first harmonic

2 x f

What is a node, what is an antinode

Nodes: zero amplitude, max destructive interference (no vibration of wave)

Antinodes: max amplitude, max constructive interference

What happens with white light incident on a diffraction grating

dsinx = nlambda

Each wavelength is diffracted a different amount

A continuous spectrum is repeated (there may be some overlapping of different orders)

Define potential difference across a component. What is the associated equation.

Energy transferred per unit charge. V = W/Q.

Why does the resistance of a filament lamp increase as current increases?

• current is flow of electrons

• as electrons move, they collide with vibrating metal ions

• the more the ions vibrate, the greater is the chance of collision

• the higher the temp, the greater the amplitude of vibration

As current increases, the temperature increases.

What is Ohm’s law

current directly proportional to potential difference across component with constant temp.